Male reproductive

Question 1

define epididymis

Answer 1

• connects the rete testis to the vas deferens

- function = storage, maturation and transport of sperm

Question 2

define vas deferens

Answer 2

• sperm transport and storage tube between epididymis and the seminal vesicles

Question 3

describe seminal vesicle

Answer 3

• produces about 60% of fluid portion of ejaculate (semen)
• seminal fluid consists of:
• -> fructose for energy
• -> prostaglandins to make cervical enviornment more favorable for sperm
• -> fibrinogen causes semen to coagulate following ejaculation
• -> seminogelin attaches to sperm and serves to suppress motility of sperm in coagulated semen

Question 4

describe prostate

Answer 4

• secretes milky fluid that contains:
• -> profibrinolysin which dissolves the coagulated semen, thus freeing sperm
• -> HCO3 neutralizes the acidic environment of their cervix allowing sperm to become more active
• -> PSA (prostate specific antigen) hydrolyzes seminogelin, which increases sperm motility

Question 5

define bulbourethral gland

Answer 5

• secretes mucus into the urethra upon arousal

- -> thought to clean the lumen of urethra and act as a lubricant

Question 6

define GnRH

Answer 6

• synthesized and released by hypothalamus

- causes the release of LH and FSH

Question 7

define LH

Answer 7

• LH binds to receptors on Leydig cells and stimualtes testosterone production and secretion
• Testosterone diffuses to Sertoli cells to facilitate spermatogenesis

Question 8

Define FSH

Answer 8

• GnRh causes the release of FSH
• FSH stimulates Sertoli cells to produce ABP (which concentrates testosterone at site of spermatogenesis)
• FSH controls sertoli cell proliferation and seminiferous tubule growth
• Stimualtes Sertoli cells to produce INHIBIN (inhibits FSH production)

Question 9

Define androgen binding protein (ABP)

Answer 9

• facilitates spermatogenesis by concentration testosterone at site of spermatogenesis

Question 10

How is the HPG-axis regulated

Answer 10

• Testosterone inhibits the release of both LH and FSH along with the release of GnRH by the hypothalamus
• Testosterone can also be converted to DHT and estradiol (both which exert negative feedback
• FSH stimulates production of INHIBIN in the sertoli cells
• -> inhibin selectively inhibits FSH production by anterior pituitary

Question 11

describe function of sertoli cells

Answer 11

• FSH controls sertoli cell
• sertoli cells produce inhibin which inhibits pituitary gonadroptropes (LH and FSH)
• sertoli cells produce ABP which concentrates testosterone at site of spermatogenesis

Question 12

function of Leydig cells

Answer 12

• stimualtes testosterone production and secretion

Question 13

what are the effects of testosterone

Answer 13

• Internal genitalia = wolffian development during gestation
• skeletal muscle = increase mass and strength during puberty
• increased erythropoiesis (more RBC)
• bone

Question 14

what are the effects of Dihydrotestosterone

Answer 14

• External genitalia = differentiation during gestation, maturation during puberty, adulthood prostatic disease
• increases growth of hair follicles during puberty

Question 15

What are the effects of Estradiol

Answer 15

• epiphyseal closure and increased bone density

- libido

Question 16

define spermiogenesis

Answer 16

• process in which spermatids differentiate into sperm by becoming elongated and developing acrosomal cap and flagellum

Question 17

define spermiation

Answer 17

• process of sperm being released into the lumen of the seminiferous tubule

Question 18

describe spermatogenesis

Answer 18

1) primordial germ cells migrate to testes and line the seminiferous tubules (called spermatogonia)
2) at time of puberty, GnRH secretion increases leading to increase in testosterone synthesis by testes
3) initiates spermatogonia to begin to proliferate
4) cells corss the tigh junctions between sertoli cells and enter adluminal compartment
5) continue to migrate towards lumen and start differentiating into spermatids (haploid cells

Question 19

describe primary hypogonadism

Answer 19

• testicular dysfunction leads to decrease in testoserone production but increased LH and FSH levels
• result from cryptorchidism or klinefelter syndrome

Question 20

describe secondary hypogonadism

Answer 20

• decrease in circulating gonadotrophins
• low testosterone in the setting of normal to low LH and FSH
• Kallmann syndrome

Question 21

list the stages of male sexual act

Answer 21

1) erection
2) lubrication
3) emission
4) ejacualtion

Question 22

define lubrication

Answer 22

parasympathetic impulses cause the bulbourethral gland to secret mucus to aid in lubrication

Question 23

define emission

Answer 23

• sympathetic impulses induce movement of spermatozoa into proximal part of the urethra

Question 24

define ejaculation

Answer 24

• reflex reaction triggered by entry of semen into proximal urethra
• singals from somatic motor efferents travel through pudendal nerve and cause rhythemic contractions of muscles at base of penis to push the semen out

Question 25

describe initiation of erection

Answer 25

• active parasympathetic induces dialtion of penile arteries and smooth muscle cells of the corpus cavernosum and corpus spongiosum
• nerve terminals release Ach, NO and vasoactive intestinal peptide (VIP)
• -> NO diffuses into vascular smooth muscles causing the activation of gunylyl cyclanse and the consequent production of cGMP
• -> cGMP causes relaxation of these smooth muscles cells causing blood to fill the sinuses